Real-time imaging of metallic supraparticle assembly during nanoparticle synthesis
Real-time imaging of metallic supraparticle assembly during nanoparticle synthesis
复制标题
纳米粒子合成过程中金属超粒子组装体的实时成像
DOI：
10.1039/d1nr05416c
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发表时间：
2022
期刊：
影响因子：
6.7
通讯作者：
Woehl, Taylor J.
中科院分区：
文献类型：
--
作者：
Wang, Mei;Park, Chiwoo;Woehl, Taylor J.
在胶体纳米颗粒合成过程中，几分钟内观察到的纳米颗粒超晶格的形成避开了对自组装的传统理解，传统的自组装理论认为，超晶格需要延长形成时间，以允许对填充缺陷进行扩散驱动的退火。尽管存在快速的超晶格生长动力学，但纳米粒子的位置退火是如何在如此短的时间尺度上发生的，目前尚不清楚。在这里，我们利用液相透射电子显微镜直接成像铂纳米颗粒在合成纳米颗粒的过程中，在数十秒内自组装成紧密堆积的超颗粒。电子束诱导铂前驱体还原形成单分散的2-3 nm铂纳米颗粒，这些纳米颗粒在几十秒内同时自组装成3D超粒子，其中一些显示出结晶有序结构域。通过改变前体化学改变粒子间相互作用(例如，静电、空间相互作用)的实验表明，超粒子的形成是由弱吸引范德华力和短程排斥空间相互作用所平衡的。生长动力学测量和颗粒间相互作用模型表明，纳米颗粒在超颗粒上的表面扩散速度比纳米颗粒附着快几个数量级，使纳米颗粒能够找到不受进入颗粒阻碍的高配位结合部位。这些结果使超粒子的快速自组装与传统的自组装模式相一致，在传统的自组装模式中，通过表面扩散进行的纳米晶位置退火发生的时间比纳米晶附着发生的时间要短得多。
Observations of nanoparticle superlattice formation over minutes during colloidal nanoparticle synthesis elude description by conventional understanding of self-assembly, which theorizes superlattices require extended formation times to allow for diffusively driven annealing of packing defects. It remains unclear how nanoparticle position annealing occurs on such short time scales despite the rapid superlattice growth kinetics. Here we utilize liquid phase transmission electron microscopy to directly image the self-assembly of platinum nanoparticles into close packed supraparticles over tens of seconds during nanoparticle synthesis. Electron-beam induced reduction of an aqueous platinum precursor formed monodisperse 2–3 nm platinum nanoparticles that simultaneously self-assembled over tens of seconds into 3D supraparticles, some of which showed crystalline ordered domains. Experimentally varying the interparticle interactions (e.g., electrostatic, steric interactions) by changing precursor chemistry revealed that supraparticle formation was driven by weak attractive van der Waals forces balanced by short ranged repulsive steric interactions. Growth kinetic measurements and an interparticle interaction model demonstrated that nanoparticle surface diffusion rates on the supraparticles were orders of magnitude faster than nanoparticle attachment, enabling nanoparticles to find high coordination binding sites unimpeded by incoming particles. These results reconcile rapid self-assembly of supraparticles with the conventional self-assembly paradigm in which nanocrystal position annealing by surface diffusion occurs on a significantly shorter time scale than nanocrystal attachment.